Prokaryotes & evolution of metabolism Flashcards
What are the earliest organisms called
Prokaryotes (Pro= before, karyos=nucleus)
Describe prokaryotes (5)
- Most ancient organism
- Unicellular
- Lived alone for 2 bill yrs
- Greatest diversity of lifestyles and habitats
- Created the Earth we know
3 prokaryote domains?
Archaea, Bacteria, Eukarya (protists, fungi, plants, animals)
Difference between prokaryotic and eukaryotic cells? (5)
Prokaryotic cells are smaller, single membraned systems not double, nucleoid, no walled organisms, no cytoskeleton
Describe bacteria (3)
- Includes most prokaryotes
- Hugely diverse in metabolism and structure
- Include photosynthetic cyanobacteria, some disease organisms
I.e. samonella
Describe archaea (1) and two differences from bacteria
- Live in harsh and extreme envrionments (extremophiles)
- Difference between bacteria is cell wall composition and details of protein synthesis
i.e. halophiles and strain 121
Why are modern prokaryotes clues to evolution of metabolism
- Some modern prokaryotes live in envrionments similar to those in early Earth; metabolism of these groups similar to those of ancient group
What are photo-autotrphs
Use light as energy, and Co2 ch4 etc. as carbon sources
What are photo-heterotroph
Use light as energy, and organics as carbon sources
What are chemo-organo-autotroph
Use organics as energy, and co2 ch4 etc. as carbon sources
What are chemo-organo- heterotraph
Use organics as energy, and organics as caron sources
What are chemo-litho-autotroph
Use inorganics as energy, and co2 ch4 etc. as carbon sources
What are chemo-litho-heterotrophs
Use inorganics as energy, and organics as carbon sources
What respiratory mode do obligate anaeroby use
Fermentaton/anaerobic respiration
What respiratory mode do faculative anaeroby use
O2 if present, or fermentation
What respiratory mode do obligate aeroby use
Always O2
Evidence that first organisms were chemoheterotrophs? (2)
- May have eaten ATP
- W/depletion of ATP in environment, selection for ability to make ATP -> evolution of glycolysis
Evidence that 1st organisms chemoautotrophs
- May have oxidised H2S & reduced forms of iron
- Deep sea vents more abundant early earth
Describe evolution of photosynthesis
First came chemotrophy then phototrophy. No fossil record. First non-oxygen producing photosynthesis then came oxygen-producing photosynthesis
Describe non-oxygenic photosynthesis (3)
- Occurs in green & purp sulfur bacteria from anoxic swamps
- H2S & light energy input, ATP & S output
- no oxygen produced
Describe oxygenic photosynthesis (3)
- Occurs in cyanobacteria
- H20 & light energy input, ATP otput
- Oxygen by product
Cyanobacteria are…
Photoautotrophs
What is responsible for high lvls of o2 in earths atmosphere
Photoautotrophs
Indications that oxygenic photosynthesis arose early (2)
- 2.7 by-old banded iron formations indicate increased atmospheric O2
- 3.5 by-old stromatolites = photosynthetic cyanobacteria
